2.1 Cereblon
At least two isoforms of the protein cereblon (CRBN) exist, which are 442 and 441 amino acids long, respectively, and CRBN is conserved from plant to human. In humans, the CRBN gene has been identified as a candidate gene of an autosomal recessive nonsyndromic mental retardation (ARNSMR). See Higgins, J. J. et al., Neurology, 2004, 63:1927-1931. CRBN was initially characterized as an RGS-containing novel protein that interacted with a calcium-activated potassium channel protein (SLO1) in the rat brain, and was later shown to interact with a voltage-gated chloride channel (CIC-2) in the retina with AMPK1 and DDB1. See Jo, S. et al., J. Neurochem, 2005, 94:1212-1224; Hohberger B. et al., FEBS Lett, 2009, 583:633-637; Angers S. et al., Nature, 2006, 443:590-593. DDB1 was originally identified as a nucleotide excision repair protein that associates with damaged DNA binding protein 2 (DDB2). Its defective activity causes the repair defect in the patients with xeroderma pigmentosum complementation group E (XPE). DDB1 also appears to function as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. CRBN has also been identified as a target for the development of therapeutic agents for diseases of the cerebral cortex. See WO 2010/137547 A1.
CRBN has recently been identified as a key molecular target that binds to thalidomide to cause birth defects. See Ito, T. et al., Science, 2010, 327:1345-1350. DDB1 was found to interact with CRBN and, thus, was indirectly associated with thalidomide. Moreover, thalidomide was able to inhibit auto-ubiquitination of CRBN in vitro, suggesting that thalidomide is an E3 ubiquitin-ligase inhibitor. Id. Importantly, this activity was inhibited by thalidomide in wild-type cells, but not in cells with mutated CRBN binding sites that prevent thalidomide binding. Id. The thalidomide binding site was mapped to a highly conserved C-terminal 104 amino acid region in CRBN. Id. Individual point mutants in CRBN, Y384A and W386A were both defective for thalidomide binding, with the double point mutant having the lowest thalidomide-binding activity. Id. A link between CRBN and the teratogenic effect of thalidomide was confirmed in animal models of zebra-fish and chick embryos. Id.
Whether binding to CRBN, the CRBN E3 ubiquitin-ligase complex, or one or more substrates of CRBN, is required for the beneficial effects of thalidomide and other drugs is yet to be established. Understanding these interactions with thalidomide and other drug targets will allow the definition of the molecular mechanisms of efficacy and/or toxicity and may lead to drugs with improved efficacy and toxicity profiles.
2.2 Compounds
A number of studies have been conducted with the aim of providing compounds that can safely and effectively be used to treat diseases associated with abnormal production of TNF-α. See, e.g., Marriott, J. B., et al., Expert Opin. Biol. Ther., 2001, 1(4): 1-8; G. W. Muller, et al., J Med Chem., 1996, 39(17): 3238-3240; and G. W. Muller, et al., Bioorg & Med Chem Lett., 1998, 8: 2669-2674. Some studies have focused on a group of compounds selected for their capacity to potently inhibit TNF-α production by LPS stimulated PBMC. L. G. Corral, et al., Ann. Rheum. Dis., 1999, 58:(Suppl I) 1107-1113. These compounds show not only potent inhibition of TNF-α but also marked inhibition of LPS induced monocyte IL1β and IL12 production. LPS induced IL6 is also inhibited by such compounds, albeit partially. These compounds are potent stimulators of LPS-induced IL-10. Id.
Compounds for the methods provided herein include, but are not limited to, the substituted 2-(2,6-dioxopiperidin-3-yl) phthalimides and substituted 2-(2,6-dioxopiperidin-3-yl)-1-oxoisoindoles described in U.S. Pat. Nos. 6,281,230 and 6,316,471, both to G. W. Muller, et al. Still other specific compounds disclosed herein belong to a class of isoindole-imides disclosed in U.S. Pat. Nos. 6,395,754, 6,555,554, 7,091,353, U.S. Publication No. 2004/0029832, and International Publication No. WO 98/54170, each of which is incorporated herein by reference.
Thalidomide, lenalidomide and pomalidomide have shown remarkable responses in patients with multiple myeloma, lymphoma and other hematological diseases such as myelodysplastic syndrome. See Galustian C, et al., Expert Opin Pharmacother., 2009, 10:125-133. These drugs display a broad spectrum of activity, including anti-angiogenic properties, modulation of pro-inflammatory cytokines, co-stimulation of T cells, increased NK cell toxicity, direct anti-tumor effects and modulation of stem cell differentiation.
For example, thalidomide and lenalidomide have emerged as important options for the treatment of multiple myeloma in newly diagnosed patients, in patients with advanced disease who have failed chemotherapy or transplantation, and in patients with relapsed or refractory multiple myeloma. Lenalidomide in combination with dexamethasone has been approved for the treatment of patients with multiple myeloma who have received at least one prior therapy. Pomalidomide may also be administered in combination with dexamethasone. U.S. Patent Publication No. 2004/0029832 A1, the disclosure of which is hereby incorporated in its entirety, discloses the treatment of multiple myeloma.
Another compound provided herein is 3-(5-amino-2-methyl-4-oxo-4H-quinazolin-3-yl)-piperidine-2,6-dione (“Compound A”), which has the following structure:
or an enantiomer or a mixture of enantiomers thereof; or a pharmaceutically acceptable salt, solvate, hydrate, co-crystal, clathrate, or polymorph thereof
Compound A can be prepared as described in U.S. Pat. No. 7,635,700, the disclosure of which is incorporated herein by reference in its entirety. The compound can be also synthesized according to other methods apparent to those of skill in the art based upon the teaching herein. In certain embodiments, Compound A is in a crystalline form described in U.S. Provisional Pat. App. No. 61/451,806, filed Mar. 11, 2011, which is incorporated herein by reference in its entirety. In some embodiments, the hydrochloride salt of Compound A is used in the methods provided herein. Methods of treating, preventing and/or managing cancers and other diseases using Compound A are described in U.S. Provisional Pat. App. No. 61/451,995, filed Mar. 11, 2011, which is incorporated herein by reference in its entirety.
Other compounds are provided in Section 5.8 herein.
Understanding the interactions of CRBN, the CRBN E3 ubiquitin-ligase complex, or one or more substrates of CRBN with thalidomide, lenalidomide, pomalidomide and other drug targets will allow the definition of the molecular mechanisms of efficacy and/or toxicity and may lead to drugs with improved efficacy and toxicity profiles.